This project is designed to examine the biochemistry and function of surface glycosyltransferases on normal and malignant cells in culture. Some of the facets of the planned research are: 1. Continued experiments to determine the optimal conditions for assaying the surface transferases on intact, living cells. The use of 3 mM AMP has been shown effective for inhibiting the hydrolysis of the sugar donor UDPgalactose, while exhibiting no interference toward the transferase reactions themselves. Other phosphatase inhibitors are being tested for their ability to inhibit breakdown of other sugar nucleotides wihout affecting transferases. 2. Purification of the solubilized, UDPgalactose: N-acetyl-glucosamine galactosyltransferase is proceeding well. The enzyme is solubilized with 100 percent yield from plasma membrane-enriched fractions of mouse fibroblasts. At least three fractions are necessary for N-acetyllactosamine synthesis from UDPgalactose. 3. The effects of retinol (Vitamin A) on membrane-catalysed transfer are being studied. Retinol stimulates galactosyl transfer in normal cell plasma membranes but not in malignant cell plasma membranes. Retinylphosphate has a greater effect with normal membranes but, again, no effect with malignant cell plasma membrane-enriched fractions. 4. The role of surface glycosylation in growth control is being tested by attempting to glycosylate 3T12 cells and measure the effect of such glycosylation on subsequent growth. The functional significance of these enzyme will be tested with the transferase inhibitor, UDP-dialdehyde.